Digital cable toning apparatus and method

ABSTRACT

A digital toner/locator employs tone packets using a 455 Khz carrier. Plural packet quanta provide multiple test modes which are advantageously selected from a probe without requiring returning to the tone generator to change mode.

BACKGROUND OF THE INVENTION

This invention relates to communication circuit testing and moreparticularly to an improved apparatus and method for providing anddetecting tone for troubleshooting and tracing communications cabling.

In working on telecommunications cabling, a typical function involvesidentifying or locating a specific cable among a number of cables. Forexample, it may be desired to locate a cable at a distant end thereofrelative to a junction point. In accordance with the prior art, a tonerlocating system is employed wherein an audio tone generator is connectedat one position on the cable, and a detector or tone probe is employedelsewhere along the cable to detect the tone in an attempt to identifyand isolate the cable carrying the tone from among other cables. Thisisolation attempt can be taking place far away from the tone generatorlocation.

Some practical problems arise in use of such toner systems. The tonerlocater system was originally employed in telephone communicationsystems but is now also employed in computer networking situations.However, for example, a 100 megabit per second computer network employscommon mode terminations, and existing toner devices do not work becausethe common mode termination configuration attenuates the tone. Thisresults in the signal being too weak due to the termination by networkequipment and it becomes difficult to detect it at a remote location.

Also, sometimes in particular wiring situations, the audio signalapplied to the cable by the tone generator is too strong and causescrosstalk and bleed into other wires on a given cable or into othercables, making it difficult to determine which cable is the actual cableto which the audio signal is being applied. Especially with a 1 Khzsignal applied to CAT5 cables, the coupling is strong and at a distancefrom the tone generator the signal strength on two adjacent cables canbe similar so as to make it difficult to determine which is the cable ofinterest. These issues can lead to wasted time, either mis-identifyingcable due to bleed, or to not being able to locate the cable due to aweak signal.

A certain level of experience is needed to effectively use such a tonersystem and to listen for the correct tone, as fluorescent lightingequipment, CRTs and other equipment which is typically present in mostcommercial buildings, can induce signals onto cabling which is thendetected by the tone probe.

A typical prior art toner system, illustrated with reference to FIG. 5,employs a 1 Khz high power square wave generator 110 which applies theaudio signal to the cable 112 under test. The generator 110 typicallyhas two states, on or off. Some generators may have a further option ofselecting the frequency of the square wave from among 2 or 3 fixedfrequencies. The generator is connected to the cable under test via 2clip leads 113 which allow connection to an individual wire or via anetwork connector 115. A hand held tone sensor probe 114, is a anamplifier, includes a sensor tip 116 and a speaker 118, and detects andconverts the square wave to an audible 1 Khz tone (or tone of whateverthe frequency is of the applied signal) audible through the speaker. Theconfiguration of the toner probe can also result in feedback, since thetone probe tip will normally be highly sensitive and can detect andfeedback signal from the speaker on the tone probe.

In use, the prior art tone generator is manually connected to the cableunder test and is turned on, and the technician then takes the probe tothe remote location, which can be far away, on a different floor in abuilding, for example. It can be that after setting the tone generatorand moving to the remote location, the technician realizes that adifferent configuration may be required. For example, the technician maynow wish to use two wires of a twisted pair in a cat5 cable as a singleconductor to provider a stronger radiating signal on the cable, byconnecting the tone generator appropriately. However, since the tonegenerator is far away, the technician must now travel back to thegenerator site and adjust the connection, then returning to the remotecable test site, consuming time.

SUMMARY OF THE INVENTION

In accordance with the invention, a cable locating system employs a testsignal generator that produces multiple types of signaling to a cableunder test and a sensor probe adapted to selectively track and reportselected ones of the signaling types as chosen by a user.

Accordingly, it is an object of the present invention to provide animproved probe and toner type cable test system.

It is a further object of the present invention to provide an improvedmethod of probe and toner testing for network cables.

It is yet another object of the present invention to provide an improvedmethod and apparatus for cable location, isolation and identificationtasks.

The subject matter of the present invention is particularly pointed outand distinctly claimed in the concluding portion of this specification.However, both the organization and method of operation, together withfurther advantages and objects thereof, may best be understood byreference to the following description taken in connection withaccompanying drawings wherein like reference characters refer to likeelements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the toner and probe system in accordancewith the invention;

FIG. 2 is a diagram illustrative of a tone packet configuration inaccordance with the invention;

FIG. 3 is a schematic representation of a toner module in accordancewith the invention;

FIG. 4 is a schematic representation of a probe module in accordancewith the invention; and

FIG. 5 is a diagram of a prior art toner/probe system.

DETAILED DESCRIPTION

Referring to FIG. 1, a block diagram of the toner and probe system, thetoner device 10 comprises a microprocessor 12 supplying modulation andline control to line drivers 14, which suitably may be attached to acable 20 via an appropriate connector such as an RJ45 connector providescarrier input in the case of a typical network. A carrier generationblock 16 also provides input to the line drivers 14.

Separate from the toner 10, a probe 22 is positionable anywhere alongthe cable and comprises an antenna 24 which furnishes signals to frontend and carrier bandpass block 26. Output from block 26 is fed to bothcarrier demodulation block 28 and analog to digital (A/D) converterblock 32, and each of blocks 28 and 32 supply signals to amicroprocessor 30. In the case of the carrier demodulation block 28, themicroprocessor is given a demodulated signal for sync detection, whilethe A/D converter provides a signal strength value to themicroprocessor.

The operation of the toner/probe system is accomplished differently fromthe prior art 1 Khz tone and probe type devices. Under control of themicroprocessor 12, the toner carrier generation block provides a 455 Khzcarrier. In order to provide a tone that can be detected even by priorart probes, the carrier is turned on and off at 1 Khz and 2 Khz rates.The 2 Khz rate is preferably employed during a sync phase discussedhereinbelow, and the 1 Khz modulation is employed at other times.

The probe 22 demodulates the 455 Khz carrier and measures the timeintervals of the modulation. Signal strength is determined by A/D block32 providing measurement of automatic gain control signal strength ofthe carrier. Suitably the toner may be configured to drive eachconductor in a cable separately, for example

In operation, the toner 10 generates a tone packet that includes varioustone phases relative to a synchronization phase. Referring now to FIG.2, a diagram of the configuration of a tone packet as * employed in apreferred embodiment, plural quanta are provided as follows, eachsuitably comprising 10 milliseconds in a particular embodiment. First,two sync quanta, Sync1 and Sync2, are provided to accommodatesynchronization of the probe to the tone packet. Sync1 suitably comprisemodulation of the 455 Khz carrier at 2 Khz and presuming an 8 conductor(4 pair) cable, involves driving one conductor pair at one polarity, 2other pairs with the opposite polarity and the 4^(th) pair is allowed tofloat (unbalanced). Sync2 floats conductor 2, drives conductors 3 and 4positive and 5 and 6 negative.

Next, a Version quantum is provided which can be employed to indicate aparticular feature. For example, in the preferred embodiment, thepresence of any energy during the Version quanta indicates a wiremapoperation is enabled and wiremap quantas (discussed hereinbelow) will bepresent. After Version, a Song# quantum indicates which “song” the probeis to employ for example when producing an audible alert for thetechnician indicating signal detection. This feature can be advantageouswhen more than one person is working at locating a cable at the sametime in the same area, so that a first technician's “tone” is notdetected by a second technician in error, leading the second technicianto mis-identify the cable, thinking it is the second technician's tonethat has been applied to the cable.

Now, a NearCable quantum is provided. The near cable phase is designedto provide minimum radiation from the cable, to minimize bleed withother cables and allow the user to precisely identify the toned cable.This phase employs the normal properties of the twisted pair cablespairs, driving opposite polarity on each of the pair wires (e.g., wires1, 3, 4 and 7 could be driven positive, while wires 2, 5, 6 and 8 weredriven negative).

Next, 4 “mega” phases are generated, Mega12, Mega36, Mega45 and Mega78,which produce maximum signal radiation from the cables by applyingunbalanced signals of one polarity on each designated pair during the 4phases, applying an opposite polarity signal on 2 of the other pairs andallowing the last pair to float. It has been determined by the inventorsthat employing this manner of signal application provides a bettersignal. That is, during Mega12 phase, the unbalanced signal is on pair1, 2, while an opposite polarity signal is applied to 2 other pairs anda 4^(th) pair is floated. During Mega36 phase, the unbalanced signal ison pair 3, 6, etc. Both wires of the particular pair are driven with thesame polarity. In the particular embodiment illustrated herein, theprobe is taking signal strength measurements during these Mega phases,and is configured to sample 4 readings in any particular quantum and usethe maximum level measured during the particular phases as a signalstrength value for this particular tone packet.

Wiremap quanta, Wire1, Wire2, Wire3, Wire4, Wire5, Wire6, Wire7, Wire8and WireSh are now optionally present if the Version quanta soindicated. In the wire map phase, all the cable wires are terminated anda “1” value is applied to each of the respective lines during therespective phase. That is, during the Wire1 quantum, the “1” is appliedto wire 1, during Wire2 quantum, the “1” is applied to wire 2, duringWire3 quantum, the “1” is applied to wire 3, during Wire4 quantum, the“1” is applied to wire 4, during Wire5 quantum, the “1” is applied towire 5, during Wire6 quantum, the “1” is applied to wire 6, during Wire7quantum, the “1” is applied to wire 7, during Wire8 quantum, the “1” isapplied to wire 8, and during WireSh, the “1” is applied to the cableshield (in the case of an 8 conductor single shield cableconfiguration). During the wiremap quanta, the energy applied to thewires is a voltage level rather than the 455 Khz carrier, the intentionof this being to eliminate signal bleed into other wires for accuratedetection.

Finally a Quiet quantum ends the packet, providing a period of time forthe AGC in the probe to recover and optimally detect the next syncphase. Also, during this time period the probe can perform otherprocessing such as analyzing or displaying results of the last tonepacket, checking for switch changes, battery level testing, etc.

In the preferred embodiment of the invention, the quanta are each 10milliseconds in length.

An advantage of employing a tone packet system such as the systemdisclosed herein is that the technician has the freedom to easily selectany one of many test modes by changing the selection at the probe end ofwhich particular packet quanta are to be detected, without requiring thetechnician to return to the toner's location and reconfigure the tonersettings or connection.

Referring now to FIG. 3 and FIG. 4, which are schematic representationsof the physical configuration of the toner 10 and probe 22, the toner isimplemented as a hand held instrument and includes a selector switch 36,suitably a rotary selector in the illustrated embodiment, for OFF, SONG1and SONG2 for selecting the particular song as discussed above. Ofcourse, more than 2 songs can be provided in other embodiments. Thetoner includes both an RJ45 type female connector 38 for attaching totypical network cables as well as two banana jacks 40 to enableconnection to non RJ-45 cables using alligator clip, banana plug leads,or the like. Visual indicators 42-48 to show the type of service towhich the device is connected (e.g. voice 44, data 42 or video 46(telephone, Ethernet or video) an can be provided in a form such asLEDs. An “Other” or unknown indicator 48 can be supplied to indicatethat the particular type of cable service is not recognized. The deviceis suitably battery powered to enhance portability, but can also beconfigured to be powered from an external supply.

A schematic probe representation is shown by FIG. 4, wherein the probemay employ an elongate shape having the antenna 24 configured at oneend. A series of visual signal strength indicators 50 are placed along alength of the body of the probe in the form of 8 LEDs to illustraterelative signal strength. The configuration can be driven to provide a 1in 256 sensitivity by driving the LEDs in a binary representation of 0to 255. A sync indicator 52, again in the form of an LED, is provided toshow that the probe has successfully synchronized with the tone packet.

A selector 54, which is a rotary selector switch in the preferredembodiment, is provided on the probe to enable selection of whichoperation mode is to be employed. In the particular embodiment theselection options are Wire Map mode (which selects the wire map functiondiscussed above in connection with the tone packet configuration), Tonemode for enabling operation in a prior art toner mode, Isolate nearcable mode (corresponding to the NearMode quanta) for preciseidentification of a toned cable, and Locate mega tone mode(corresponding to the Mega quanta discussed above) for detecting themaximum radiation mode of the cable packet quanta to enable maximumrange and detection when a cable is terminated into a network devicesuch as a switch. When in this mode, which can also be called a roughlocate mode, the line of 8 LEDs are driven to indicate whether thesignal is getting stronger or weaker. If the signal is getting stronger(that is, if the probe is getting closer to the toned cable), the LEDsare illuminated in a pattern so as to appear to sweep toward the antennatip of the probe. Alternatively, if the signal is getting weaker, theLEDs are illuminated to appear to sweep away from the antenna tip of theprobe, providing a technician with an idea of whether the technician isgetting closer or farther from the toned cable.

The probe further includes a speaker 56 which is configured to emit anaudio signal to indicate that tone packets are detected. However, unlikethe prior art which merely detected and reproduced the actual signalfrequency of the applied tone, the audio produce by the speaker on theinventive probe can be configured in any manner. Suitably a differentaudio program is produced depending on whether song 1 or song 2(discussed above) is detected. An RJ45 type connector 58 is alsoprovided to the probe, for connecting a cable for use in wiremap mode todetect the wiring configuration in conjunction with the tone packetwiremap quanta. Cable wiring errors (or lack thereof) can be determined.

The various operations described above for the toner and probe aregoverned by the respective microprocessors in the toner and the probe.

Use of the 455 Khz carrier provides advantages such as: immunity to 60Hz noise and fluorescent lighting noise; since the probe is notproducing the same audible frequency as it is detecting, the problem ofprobe feedback that is common in prior art toner/probe systems iseliminated. Further, the probe gain is split between the 455 Khz and 1Khz paths, providing a more stable system.

The invention solve the problem in toning cable where sometimes thesignal is too strong and causes bleed and other times the signal is tooweak due to termination by network equipment, avoiding a technicianhaving many wasted hours, either from mis-identifying cable due tobleed, or from not being able to locate the cable due to a weak signal.

Accordingly an improved toner/probe system is provided.

While a preferred embodiment of the present invention has been shown anddescribed, it will be apparent to those skilled in the art that manychanges and modifications may be made without departing from theinvention in its broader aspects. The appended claims are thereforeintended to cover all such changes and modifications as fall within thetrue spirit and scope of the invention.

1. A toner/probe system, comprising: a toner adapted to generate andsupply a tone packet to a cable under test, wherein said toner suppliesa carrier signal as at least part of said tone packet; and a probeadapted to detect said tone packet as propagated via the cable undertest.
 2. A toner/probe system according to claim 1, wherein said tonepacket comprises: a synchronization portion; and a data portion.
 3. Atoner/probe system according to claim 2, wherein said data portioncomprises plural portions providing different testing modes.
 4. Atoner/probe system according to claim 3, wherein said testing modes areselected from the group consisting of: a cable isolate mode and a cablelocate mode.
 5. A toner/probe system according to claim 3, wherein saidtesting mode comprises a wire continuity test mode for location one ormore wires separately from other wires.
 6. A toner/probe systemaccording to claim 3, wherein said testing mode comprises a wire mapmode.
 7. A toner/probe system according to claim 1 wherein said carriersignal is other than an audible frequency.
 8. A toner/probe systemaccording to claim 1 wherein said toner comprises a selector forselecting an operation mode.
 9. A toner/probe system according to claim1 wherein said toner comprises a song selector for selectively applyingone of at least two distinguishable tone packets.
 10. A toner/probesystem according to claim 1, wherein said probe comprises a detector fordetecting said tone packet and operatively responding to portionsthereof.
 11. (canceled)
 12. (canceled)
 13. A method for locating acable, comprising the steps of: applying a tone packet to a cable at oneposition thereof, wherein said tone packet employs a carrier signal asat least part of said tone packet; and employing a sensor responsive tosaid tone packet to locate said cable at another position thereof. 14.The method according to claim 13, wherein said applied tone packetcomprises: a synchronization portion; and a data portion.
 15. The methodaccording to claim 14, wherein said data portion comprises pluralportions providing different testing modes.
 16. The method according toclaim 15, wherein said testing modes are selected from the groupconsisting of: a cable isolate mode and a cable locate mode.
 17. Themethod according to claim 15, wherein said testing mode comprises a wirepair test mode for location one or more wire pairs separately from otherwire pairs.
 18. The method according to claim 15, wherein said testingmode comprises a wire map mode.
 19. The method according to claim 13,wherein said carrier signal is other than an audible frequency.
 20. Atoner/probe system according to claim 1 wherein said carrier signal isturned on and off at an audio frequency rate.
 21. A toner/probe systemaccording to claim 20 wherein said audio frequency rate is 1 Khz or 2Khz.
 22. A toner/probe system according to claim 1 wherein said tonepacket comprises plural quanta.
 23. The method according to claim 13,wherein said carrier signal is turned on and off at an audio frequencyrate.
 24. The method according to claim 23 wherein said audio frequencyrate is 1 Khz or 2 Khz.
 25. The method according to claim 13, whereinsaid carrier signal frequency is other than a tone frequency.
 26. Atoner/probe system according to claim 1 wherein said carrier signalfrequency is other than a tone frequency.